To add the CA certificate in Mozilla Firefox, follow the instruction:

Prerequisites

Please look on Add a Root Certificate

Procedure

  1. Open the browser
  2. Click the Open menu button in the upper right corner
  3. Choose Options
    Figure 1. Open Mozilla Firefox Options
  4. Open Privacy & Security tab
  5. Scroll down till Certificates section
  6. Click View Certificates… button
    Figure 2. Privacy & Security
  7. In Certificate Manager window click on Import… under Authorities tab
    Figure 3. Certificate Manager
  8. Navigate to the folder where the downloaded certificate is stored
  9. Click on ca.cert.pem
  10. Click Open
    Figure 4. Choose Certificate
  11. In Downloading Certificate window, set up checkbox Trust this CA to identify websites and click OK
    Figure 5. Downloading Certificate

Results

Root certificate is successfully imported